Various recording apparatus are used to form images on recording media. For example, images can be formed on a recording media by mounting the recording media on a support and operating a recording head comprising a plurality of individually addressable recording channels to form the images on the media. In such systems, images can be formed by various processes. For example, the recording channels can be operated to emit radiation beams to form an image on the recording media. In other examples, the recording channels can be operated to emit an image forming material towards the recording media to form an image thereon. In typical inkjet applications, various recording channels are used to emit drops of image forming material to form images on various recording media. In many cases, each recording channel is operated to form a unit element of image typically referred to as an image dot or image pixel.
Various image features are formed on a recording media by various image pixels patterns which include halftone patterns, stochastic patterns, and hybrid patterns. It is a common desire to form high quality images with reduced levels of artifacts. In particular, the final quality of the formed image features is typically dependant on the visual characteristics associated with the image pixel patterns themselves as well as the visual characteristics associated with the manner in which various image pixel patterns combine with other image pixel patterns.
Increased productivity requirements have led to the use of recording heads with an ever increasing numbers of recording channels. Despite these larger numbers however, it is necessary in many applications to merge a plurality of sub-images to create a desired image. Merging sub-images without artifacts along their merged borders is desirable. Banding refers to an artifact that may appear as regular or random patterns of density variations. Typically, banding can occur in the regions where various sub-images are merged. Artifacts such as banding can be caused by placement errors of the image pixels on the recording media or by visual characteristic variations among the image pixels themselves.
Various factors can adversely affect the placement requirements and/or the visual characteristics of formed image pixels. Errors in a required placement can arise from different causes including spatial misalignment between the recording head and the recording media during the formation of the image pixels. Operating variations among the various recording channels (e.g. radiation beam intensity variations) can lead to visual characteristics variations among the image pixels (e.g. density variations). The visual characteristics and/or the placement requirements of formed image pixels can also vary as function of the image data that is used to control the formation of the image pixels. One method of reducing artifacts such as banding is to design and manufacture the recording apparatus to exacting specifications. This approach however can quickly become cost prohibitive.
There is a need for effective and practical methods and systems that can permit the formation of a visually pleasing image from a plurality of sub-images. There remains a need for effective and practical methods and systems that can reduce visual artifacts associated with various misalignments between sub-images comprising various patterns of image pixels.